Electronic apparatus

Abstract

To provide a technology capable of suppressing electromagnetic noise emitted from a housing.SOLUTION: An electronic apparatus is configured that includes a substrate, a housing that houses the substrate, a fan fixed to an opening formed in the outer surface of the housing, and an electromagnetic shielding member that is fixed between the housing and the fan at the opening and that, when attached to the opening, forms a divided opening having an opening diameter that is smaller than the opening diameter of the opening and smaller than 1 / 2 the wavelength of electromagnetic noise.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an electronic device. [Background technology]

[0002] In electronic devices in which a substrate on which circuits such as chips and wiring are formed is housed in a housing, a fan may be attached to the outer surface of the housing to cool the circuits such as chips. For example, see Patent Document 1. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-211103 Summary of the Invention [Problem to be solved by the invention]

[0004] When attaching a fan to a housing, a large opening is often formed in the housing to avoid obstructing the airflow, and the fan is then attached to that opening. However, when a large opening is formed, electromagnetic noise is more likely to leak from inside the housing. The present invention has been made in view of the above-mentioned problems, and has an object to provide a technique capable of suppressing electromagnetic noise radiated from a housing. [Means for solving the problem]

[0005] In order to achieve the above object, an electronic device is configured that includes a substrate, a housing that houses the substrate, a fan fixed to an opening formed in the outer surface of the housing, and an electromagnetic shielding member that is fixed between the housing and the fan at the opening and that, when attached to the opening, forms a divided opening having an opening diameter that is smaller than the opening diameter of the opening and smaller than 1 / 2 the wavelength of electromagnetic noise.

[0006] That is, in a configuration in which a fan circulates gas inside and outside the housing through an opening provided in the housing, a divided opening is formed by dividing the shape of the opening with an electromagnetic shielding member. The electromagnetic shielding member is attached to the housing and electrically connected to the housing, thereby functioning as an electromagnetic shield. When an opening is present in the electromagnetic shield, if the opening diameter of the opening is equal to or greater than half the wavelength of the electromagnetic noise, the electromagnetic noise inside the housing will be efficiently radiated to the outside. Therefore, the opening diameter of the divided opening is configured to be smaller than half the wavelength of the electromagnetic noise. With this configuration, it is possible to suppress the electromagnetic noise radiated from the housing compared to a configuration in which the opening diameter of the divided opening is equal to or greater than half the wavelength of the electromagnetic noise. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1A is a perspective view of the electronic device, and FIG. 1B is a side view of the electronic device, showing the surface to which the fan is fixed. [Figure 2] Fig. 2A is a side view showing the surface shown in Fig. 1B with the fan removed, and Fig. 2B is a view of the surface shown in Fig. 1B as seen from the back side (from inside the housing). [Figure 3] FIG. 1 is an exploded perspective view of an electronic device. DETAILED DESCRIPTION OF THE INVENTION

[0008] Here, the embodiments of the present invention will be described in the following order. (1) Electronic device configuration: (2) Other embodiments:

[0009] (1) Electronic device configuration: An electronic device 10 according to one embodiment of the present invention includes a housing 20 and a fan 30. Fig. 1A is a perspective view of the electronic device 10, and Fig. 1B is a side view of the surface of the electronic device 10 to which the fan 30 is fixed. Fig. 2A is a side view of the surface shown in Fig. 1B with the fan 30 removed. Fig. 2B is a view of the surface shown in Fig. 1B as seen from the back side (from inside the housing 20). Fig. 3 is an exploded perspective view of the electronic device 10.

[0010] The electronic device 10 realizes various functions by circuits formed on a substrate (not shown) housed within the housing 20. That is, chips and various elements are mounted on the substrate, and together with the wiring formed on the substrate, a predetermined circuit is configured.

[0011] The housing 20 has a general shape of a rectangular parallelepiped, and each side of the rectangular parallelepiped is made of a metal plate member. In this specification, the directions parallel to the side surfaces of the housing 20 are defined as the x-direction and y-direction, and the direction perpendicular to the xy plane is defined as the z-direction.

[0012] A recess 21a (see FIG. 3) bent inward from one side surface 21 of the housing 20 is formed, and the fan 30 is fixed to the recess 21a. The fan 30 has a rough rectangular parallelepiped shape and is sized and shaped to fit into the recess 21a. By fixing the fan 30 to the recess 21a, the fan 30 is positioned inside the side surface of the housing 20 and is configured not to protrude outside the side surface of the housing 20 (in the negative y-axis direction shown in FIG. 1A).

[0013] An opening 21b is formed inside the recess 21a of the housing 20 (see FIG. 3). That is, inside the recess 21a, portions 21c including holes are formed at the four corners of the xz plane, but no wall surfaces are formed other than these portions, forming the opening 21b.

[0014] Fan 30 is fixed by screws 31 into holes in portion 21c formed around opening 21b. Fan 30 is a device that rotates to cause gas to flow, and in this embodiment includes hub 32 and propeller 33. Note that while hub 32 and propeller 33 are shown in FIG. 2B, the lead lines of propeller 33 indicate the area through which propeller 33 passes as it rotates, and the specific shape of propeller 33 is omitted.

[0015] The hub 32 is a cylindrical portion that includes the rotation axis Ax of the fan 30, and includes a portion that rotates together with the propeller 33 and a portion that does not rotate and is fixed to the main body of the fan 30. The cylindrical portion of the hub 32 is centered on the rotation axis Ax and has a radius Rh, which is the size in the direction perpendicular to the rotation axis Ax (called the radial direction). The propeller 33 is attached to the rotating portion of the hub 32. As this portion rotates, the propeller 33 rotates about the rotation axis Ax, causing the gas to flow mainly in the direction along the rotation axis Ax (the y direction).

[0016] In the recess 21a of the housing 20, an electromagnetic shielding member 40 is fixed between the housing 20 and the fan 30. The electromagnetic shielding member 40 is a thin, plate-like member and includes an annular portion 41 and a plurality of radiating portions 42 extending radially from the annular portion. The annular portion 41 forms a circular ring, and the radius Rs, which is the radial size of the annular portion 41, is shown. In this embodiment, the center of the ring formed by the annular portion 41 coincides with the rotation axis Ax, and the radius Rs is smaller than the radius Rh of the hub 32. Therefore, the annular portion 41 is disposed radially inward of the hub 32.

[0017] In the radial direction, the airflow caused by the propeller 33 does not pass through the area where the hub 32 is located, but passes through the area where the propeller 33 is located. Therefore, in this embodiment, the annular portion 41 is disposed radially inward of the hub 32, thereby reducing the possibility that the annular portion 41 will obstruct the airflow. Furthermore, the annular portion 41 is a ring, and a hole is formed in the area including the rotation axis Ax. Therefore, even if an airflow is generated near the annular portion 41, the annular portion 41 is unlikely to obstruct the airflow.

[0018] In this embodiment, the radiating portions 42 extend radially from six positions on the annular portion 41. The extending directions of the radiating portions 42 are directions in which the rotation angle around the rotation axis Ax is at approximately regular intervals (approximately 60° intervals). The width of the radiating portions 42 is approximately constant. In FIGS. 2A and 2B, the two radiating portions 42 extending in the x direction extend linearly, but the other four radiating portions 42 have portions that extend radially and portions that extend in the vertical direction. Of course, the shapes may be various.

[0019] In this embodiment, the electromagnetic shield member 40 is a metal member that is fixed to the housing 20 at the ends of the radiation portions 42. In this embodiment, the electromagnetic shield member 40 is fixed to the opening 21b by the screws 31, the protrusions inserted into the holes, and the elasticity of the electromagnetic shield member. Specifically, the electromagnetic shield member 40 has holes 42a formed at the tips of the four radiation portions 42 that correspond to the portions 21c formed at the four corners of the opening 21b.

[0020] In this embodiment, two of these holes 42a are screw holes into which screws 31 are inserted. As shown in Figures 1A, 1B, and 3, screw holes are also formed in the fan 30, and screws 31 are inserted into two diagonally opposite screw holes, and these screws 31 reach holes 42a in the electromagnetic shield member 40 and further reach screw holes formed in the housing 20. In other words, the fan 30, the electromagnetic shield member 40, and the housing are fixed to one another by the screws 31.

[0021] Furthermore, among holes 42a, the diagonal hole into which screw 31 is not inserted is a hole into which protrusion 22 formed on housing 20 is inserted (see FIG. 2A). Protrusion 22 protrudes outward from housing 20 (in the negative y-axis direction). When protrusion 22 is inserted into hole 42a, protrusion 22 engages with hole 42a, and electromagnetic shield member 40 is fixed to housing 20.

[0022] Furthermore, the electromagnetic shield member 40 is provided with portions 42b and 42c that are fixed to the housing 20 using the elasticity of the electromagnetic shield member 40. Of these portions, portions 42b located at both ends in the z direction extend toward the inside of the housing 20. Of the portions 42b, the portion 42b located at the upper end (the positive side of the z direction) is biased upward within the housing 20. Of the portions 42b, the portion 42b located at the lower end (the negative side of the z direction) is biased downward within the housing 20. Therefore, when the electromagnetic shield member 40 is placed in the recess 21a and the portion 42b is inserted into the housing 20, the portion 42b is biased upward and downward within the housing 20, and the elastic force fixes the electromagnetic shield member 40 to the opening 21b.

[0023] Furthermore, the portions 42c are biased against the wall surfaces of the recessed portion 21a outside the housing 20. That is, in FIG. 3, the portions 42c are formed by bending the tips of the radiation portions 42 outward (in the negative y-axis direction), and the distance between the portions 42c is slightly greater than the width of the recessed portion 21a in the x-direction. Therefore, when the electromagnetic shield member 40 is disposed in the recessed portion 21a and the portions 42c are pushed into the recessed portion 21a while bending, a force is applied to the recessed portion 21a from the portions 42c to spread the wall surfaces of the recessed portion 21a in the x-direction from the portions 42c, and the elastic force fixes the electromagnetic shield member 40 to the opening 21b. With the above configuration, the electromagnetic shield member 40 can be easily fixed between the fan 30 and the housing 20.

[0024] As described above, electromagnetic shield member 40 has radiating portions 42 extending radially from annular portion 41, and therefore divides opening 21b into a plurality of divided openings. In this embodiment, the divided openings are regions surrounded by two radiating portions 42 and housing 20. In FIG. 2A, one of the divided openings is indicated by a dashed line and is designated divided opening 21b1. The divided openings are regions formed by dividing opening 21b before division, and therefore have a smaller opening diameter than opening 21b.

[0025] In this embodiment, the opening diameter of the dividing opening is configured to be smaller than half the wavelength of the electromagnetic noise. Note that the electromagnetic noise assumed here is an electromagnetic wave radiated from a noise source on a board housed in housing 20, and has a predetermined frequency, and therefore a predetermined wavelength.

[0026] The opening diameter of the divided opening is the maximum diameter in a direction parallel to the xz plane. That is, among the lines that cross the divided opening in a direction parallel to the xz plane, the line segment that has the longest length between two intersections with the inner periphery of the divided opening is identified, and that length is taken as the opening diameter. In FIG. 2A, the opening diameter Dd of divided opening 21b1 is indicated by a dashed arrow.

[0027] The opening diameter of each of the divided openings formed by the electromagnetic shielding member 40 and the housing 20 is smaller than half the wavelength of the electromagnetic noise. If the opening diameter of the divided openings is equal to or larger than half the wavelength of the electromagnetic noise, the electromagnetic noise inside the housing 20 will be efficiently radiated to the outside. However, if the opening diameter of the divided openings is smaller than half the wavelength of the electromagnetic noise, as in this embodiment, the radiation of the electromagnetic noise is suppressed. Therefore, according to this embodiment, it is possible to suppress the electromagnetic noise radiated from the housing 20 compared to a configuration in which the opening diameter of the divided openings is equal to or larger than half the wavelength of the electromagnetic noise.

[0028] Furthermore, in this embodiment, on the outer periphery of each divided opening, the maximum value of the distance between the portions connecting the electromagnetic shielding member 40 and the housing 20 is smaller than half the wavelength of the electromagnetic noise. Specifically, the radiation portion 42 of the electromagnetic shielding member 40 that forms the outer periphery of the divided opening has portions (hole 42a, portion 42b, portion 42c) that are connected to the housing 20. When any two pairs of portions that exist on the outer periphery of one divided opening are selected and the distance between the selected portions is determined, the maximum value of the distances is smaller than half the wavelength of the electromagnetic noise.

[0029] For example, among the divided openings shown in Fig. 2A, divided opening 21b2 located at the bottom left has hole 42a, portion 42b, and portion 42c as portions where radiation portion 42 and housing 20 are connected. Among the distances between any two portions selected from these portions, the maximum distance is distance L1 between portions 42c and 42b. In this embodiment, distance L1 is smaller than half the wavelength of the electromagnetic noise.

[0030] The portion where the radiation portion 42 of the electromagnetic shield member 40 is connected to the housing 20 is an essential portion for enabling the metallic electromagnetic shield member 40 to function as an electromagnetic shield. That is, the electromagnetic shield member 40 functions as an electromagnetic shield by being electrically connected to the housing 20 and at the same potential. With such a configuration in which the maximum value of the distance between portions that are important for achieving the function as an electromagnetic shield is less than half the wavelength of the electromagnetic noise, it is possible to more effectively reduce the possibility that the electromagnetic noise to be suppressed will be radiated outside the housing 20.

[0031] (2) Other embodiments: The above embodiment is one example of how the present invention can be implemented, and various other embodiments are possible. For example, the size, type, and shape of the fan 30 are not limited to those of the above embodiment, and the size and shape of the electromagnetic shield member 40 are not limited to those of the above embodiment.

[0032] The substrate has chips, wiring, etc. formed thereon, and includes a source of electromagnetic noise. Electromagnetic noise can occur in various frequency bands, but electromagnetic waves in a specific frequency band may be considered to be electromagnetic noise to be suppressed. The chip is an integrated circuit or the like fixed to the substrate, and there are no restrictions on the size, type, signal frequency, etc. The chip can be a noise source that radiates electromagnetic waves.

[0033] The housing is a hollow component that houses the substrate, and its shape is not limited. Typically, it is a hollow rectangular parallelepiped as in the above-described embodiment, but other shapes are also possible. Furthermore, components other than the substrate, such as a heat sink or various partition members, may be housed inside the housing.

[0034] The fan may be fixed to an opening formed in the outer surface of the housing. That is, the fan may be fixed to the opening, and as the fan rotates, gas may flow inside and outside the housing through the opening. The fan may be any device that generates an airflow, and the type, shape, and size of the fan are not limited. However, it is preferable that the rotating part of the fan has a diameter equal to or larger than the diameter of the opening, and that the gas flows throughout the entire opening.

[0035] The electromagnetic shielding member is fixed between the housing and the fan at the opening, and by attaching it to the opening, it is possible to form divided openings whose diameters are smaller than the opening diameter of the opening and smaller than half the wavelength of the electromagnetic noise. In other words, the electromagnetic shielding member is configured to divide a large opening so that the maximum diameter after division is smaller than half the wavelength of the electromagnetic noise.

[0036] Furthermore, when the electromagnetic shielding member forms the dividing opening, the dividing opening may be formed by the electromagnetic shielding member alone, or by both the electromagnetic shielding member and the housing. The dividing opening is a part of the opening formed in the housing, and appears when the electromagnetic shielding member divides the opening into separate openings. The shape of the dividing opening is not limited and may be various shapes. However, the maximum diameter of the dividing opening is smaller than 1 / 2 the wavelength of the electromagnetic noise.

[0037] Electromagnetic noise is electromagnetic waves emitted from noise sources such as chips formed on a substrate. The electromagnetic noise has a predetermined frequency to be suppressed, and its wavelength is also predetermined. Therefore, the opening diameter of the dividing opening is determined based on the wavelength.

[0038] The number of divided openings formed by the electromagnetic shielding member is not limited, as long as the opening diameter of each divided opening is set so that it is smaller than half the wavelength of the electromagnetic noise. For example, the number of divided openings may be set so that it is the smallest number possible within the range in which the opening diameter of the divided opening is smaller than half the wavelength of the electromagnetic noise. With this configuration, the radiation portion of the electromagnetic shielding member that forms the outer periphery of the divided openings can be minimized, thereby preventing excessive obstruction of the airflow generated by the fan. [Explanation of symbols]

[0039] 10...electronic device, 20...casing, 21...side surface, 21a...recess, 21b...opening, 21b1...divided opening, 21b2...divided opening, 21c...portion, 22...protrusion, 30...fan, 31...screw, 32...hub, 33...propeller, 40...electromagnetic shielding member, 41...annular portion, 42...radiating portion, 42a...hole, 42b, 42c...portion

Claims

1. A substrate; a housing that houses the substrate; a fan fixed to an opening formed in an outer surface of the housing; an electromagnetic shielding member fixed between the housing and the fan at the opening, the electromagnetic shielding member being attached to the opening to form a divided opening having an opening diameter smaller than the opening diameter of the opening and smaller than half the wavelength of electromagnetic noise; An electronic device comprising:

2. a maximum value of a distance between portions connecting the electromagnetic shielding member and the housing on the outer periphery of each of the divided openings is smaller than half the wavelength of electromagnetic noise; The electronic device according to claim 1 .

3. The fan is a cylindrical hub including a rotation axis; a propeller attached to the hub, The electromagnetic shielding member is an annular portion disposed radially inward of the hub in a radial direction perpendicular to the rotation axis; a plurality of radiating portions extending radially from the annular portion; 3. The electronic device according to claim 1.

4. The electromagnetic shielding member is a portion of the electromagnetic shield member that is fixed to the opening by elasticity of the electromagnetic shield member; 3. The electronic device according to claim 1.

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